JP7235168B2 - Manufacturing method of polymer dispersed liquid crystal display element and polymer dispersed liquid crystal display element - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystal material, a method for producing a polymer dispersed liquid crystal display element having a light control layer made of a polymeric substance that is a polymer of a polymerizable composition, and the polymer dispersed liquid crystal display element. . Polymer-dispersed liquid crystal display elements are used for optical shutters used for light control in digital cameras and smartphones, light scattering plates for light sources for displays, light guide plates, reflectors for reflective displays and transparent displays, and light control elements. Light control elements include glass windows, doors, partitions, private glass, etc. Light control elements used in buildings such as houses and buildings, glass windows, mirrors, roofs such as automobiles, airplanes, ships, Including articles such as light control elements used in transportation vehicles such as trains, decorative light control elements such as sunglasses, eyeglasses, sun visors, clocks, mirrors and reflectors.

A polymer-dispersed liquid crystal display element produced using a polymer-dispersed liquid crystal composition does not require a polarizing plate, and thus a TN, STN, IPS or VA mode liquid crystal display element using a conventional polarizing plate can be used. Compared to , it has the advantage of realizing a brighter display and the element structure is simple, so it is used for optical shutter applications such as light control glass, various optical element applications, and segment display applications such as watches. A polymer dispersion type liquid crystal display element controls the scattering and transmission of light by changing the state in which the orientation of liquid crystal molecules is disturbed by a polymer to the state in which the liquid crystal compound is oriented in one direction by applying a voltage. is. It becomes cloudy when scattering and transparent when transmitting.

There are several types of polymer-dispersed liquid crystal elements. For example, a type called NCAP (Patent Document 1) in which small droplets of a liquid crystal substance are dispersed in a polymer is suitable for a large area. Driving voltage was high. As a method to improve it, a type called PDLC or PNLC, which uses polymerization phase separation caused by irradiating a mixture of polymerizable monomers with a liquid crystal material with ultraviolet rays (Patent Document 2), etc., has been proposed. The PNLC type, in which a polymer network structure is formed in a continuous phase of liquid crystal, has been applied to optical elements, display elements, and the like that require a high degree of transparency. In this PNLC type, a polymer dispersed liquid crystal display element having desired physical properties can be obtained by controlling not only the physical properties of the liquid crystal composition used and the monomer composition used as the polymer forming material, but also the size of the network structure of the polymer. can be made.

These polymer-dispersed liquid crystal elements manufactured by irradiating ultraviolet rays tend to be unable to obtain a uniform transmission/scattering state, drive voltage, and halftone state unless the manufacturing process is properly controlled. There were sometimes problems such as a decrease in yield. In Patent Document 3, studies have been made to keep the ultraviolet irradiation intensity distribution within a certain range, but this alone has not solved the problem.

JP-A-8-286162 US Pat. No. 5,304,323 JP-A-5-066387

The problem to be solved by the present invention is to find, in a method for manufacturing a polymer-dispersed liquid crystal element, precise manufacturing conditions for obtaining a uniform scattering state, a uniform transparent state, and a uniform driving voltage state. An object of the present invention is to obtain a polymer-dispersed liquid crystal device having properties.

The inventors of the present invention have made intensive studies to solve the above problems, and as a result, a polymer-dispersed liquid crystal display device having excellent uniformity can be obtained by manufacturing the polymer-dispersed liquid crystal display device under specific manufacturing conditions. The present inventors have found that it can be obtained, and have completed the present invention.

That is, in the present invention, a material for forming a light control layer containing a liquid crystal material and a polymerizable composition is interposed between two substrates, at least one of which has an electrode layer, and at least one of which is transparent. By polymerizing the polymerizable composition, the average value A of the top 10% and the average value B of the bottom 10% in the transmittance distribution of the light control layer having a light control layer made of a liquid crystal material and a polymer substance are obtained. A method for manufacturing a polymer dispersed liquid crystal display element in which the ratio of the difference (A - B) to the average value B of the lower 10% ((A - B)/B x 100) is 200% or less, wherein the liquid crystal is irradiated with ultraviolet rays A polymer-dispersed liquid crystal display element characterized in that the minimum reflectance of ultraviolet rays on the installation surface of the liquid crystal display element located on the opposite side of the ultraviolet irradiation lamp as viewed from the display element is 50% or more of the maximum reflectance. A manufacturing method and a polymer dispersed liquid crystal display element are provided.

By using the manufacturing method of the present invention, a polymer dispersed liquid crystal display element having excellent scattering state, transparent state, and excellent uniformity in driving voltage can be obtained.

FIG. 2 is a schematic diagram showing a back plate used when manufacturing the polymer dispersed liquid crystal display element of the present invention by UV irradiation. FIG. 2 is a schematic diagram of grids of measurement points when measuring physical properties of the polymer dispersed liquid crystal display element of the present invention.

The polymer-dispersed liquid crystal display element obtained by the production method of the present invention comprises a polymer-dispersed liquid crystal composition comprising a liquid crystal composition (liquid crystal material), a polymerizable composition, and a polymerization initiator on two ITO-attached glass substrates. It is placed between two substrates, at least one of which has an electrode layer between them, at least one of which is transparent, by means of injection or the like, and by irradiating the light-modulating layer with ultraviolet rays, a phase of a liquid crystal phase and a polymer phase is formed. It can be obtained by inducing separation and polymerizing the polymerizable monomer composition to form a polymer network structure in the liquid crystal phase or by forming a liquid crystal droplet structure in the polymer. It is important to control the ultraviolet curing process and the steps leading up to the ultraviolet curing process to obtain uniform properties. Also, the influence of the control of the manufacturing process changes greatly depending on the liquid crystal composition to be used.

As an index of uniform characteristics, the in-plane transmittance of the polymer dispersed liquid crystal display element is evaluated, and the difference (AB) between the average value A of the top 10% and the average value B of the bottom 10%, The ratio of the lower 10% to the average value B ((AB) / B × 100) is included, and this value is preferably 200% or less, more preferably 100% or less, and 50% or less. It is even more preferred to be 30% or less, most preferably 30% or less.

The transmittance of the present invention indicates a value measured using an LCD-5200 LCD evaluation device manufactured by Otsuka Electronics Co., Ltd. with a B lens under the condition of aperture S, which is equivalent to the condition of a condensing angle of 3.2 °. be.

A method for producing the polymer dispersed liquid crystal display element of the present invention will be described. The polymer-dispersed liquid crystal display device having uniform properties as described above can be produced by the following method. After sandwiching a liquid crystal material and a light modulating layer forming material containing a polymerizable composition between two substrates at least one of which has an electrode layer and at least one of which is transparent, heat or active energy rays are applied. By polymerizing the polymerizable composition by irradiation and inducing phase separation from the liquid crystal composition, a light control layer comprising the liquid crystal composition and a transparent polymeric substance can be formed and obtained. In particular, a method of inducing phase separation from the liquid crystal composition by irradiating ultraviolet rays to polymerize the polymerizable compound is preferable.

The two substrates can be made of a flexible transparent material such as glass or plastic, and one can be made of an opaque material such as silicon. A transparent substrate having a transparent electrode layer can be obtained, for example, by sputtering indium tin oxide (ITO) on a transparent substrate such as a glass plate. Further, by using a transparent substrate with low wavelength dispersion, the light scattering ability of the device of the present invention is enhanced, and the reflectance and contrast are improved, which is more preferable. Examples of transparent substrates with low wavelength dispersion include borosilicate glass, plastic transparent films such as polyethylene terephthalate or polycarbonate, and transparent substrates coated with dielectric multilayer films using 1/4λ light interference conditions.

Moreover, a polymer film, an alignment film, a _SiO2 film, a SiNx film, and a color filter can be arranged on the substrate, if necessary. As the alignment film, for example, a polyimide alignment film, a photo-alignment film, or the like can be used. As a method for forming an alignment film, for example, in the case of a polyimide alignment film, a polyimide resin composition is applied onto the transparent substrate and thermally cured at a temperature of 180° C. or higher. Generally, in the case of a polymer dispersed liquid crystal display element, rubbing treatment using cotton cloth, rayon cloth, or the like is not performed.

A color filter can be produced by, for example, a pigment dispersion method, a printing method, an electrodeposition method, a dyeing method, or the like. An example of a method for producing a color filter by a pigment dispersion method is to apply a curable coloring composition for a color filter onto the transparent substrate, apply a patterning treatment, and cure by heating or light irradiation. By performing this process for each of the three colors of red, green, and blue, a pixel portion for a color filter can be produced. In addition, a pixel electrode provided with an active element such as a TFT, a thin film diode, a metal insulator metal resistivity element, or the like may be provided on the substrate.

The substrates are opposed so that the transparent electrode layer is on the inside. At that time, the spacing between the substrates may be adjusted via spacers. In this case, it is preferable to adjust the thickness of the obtained light control layer to be 1 to 100 μm. Among them, 2 to 50 μm is preferable, 2 to 30 μm is more preferable, 5 to 25 μm is still more preferable, and 5 to 15 μm is most preferable. Examples of spacers include glass particles, plastic particles, alumina particles, photoresist materials, and the like. After that, a sealant such as an epoxy-based thermosetting composition is screen-printed on the substrate, the substrates are bonded together, and the sealant is cured by heating or ultraviolet curing.

As a method for sandwiching the light control layer forming material between the two substrates, a normal vacuum injection method may be used, but it is also preferable to perform dropping or coating such as an ODF method or an ink jet method. It is preferable that the light-modulating layer-forming material is in a uniform isotropic state from the vacuum injection, dropping, or coating step to the ultraviolet irradiation for forming a network structure in the light-modulating layer. This uniform isotropic state can be obtained at a temperature equal to or higher than the nematic-isotropic transition point (Tni(PNM)) of the polymer-dispersed liquid crystal composition. That is, it is preferable to maintain the temperature of the polymer-dispersed liquid crystal composition at a temperature equal to or higher than Tni(PNM) during the period from the injection or the like until the ultraviolet irradiation. If the temperature is set to Tni (PNM) or lower, the liquid crystal composition concentration rich phase and the polymerizable composition concentration rich phase may separate into two phases, resulting in a non-uniform state. It is difficult to obtain a uniform state even if the injection or the like is performed with . In particular, when the two-phase separation occurs by lowering the temperature to Tni(PNM) or lower after being sandwiched between two substrates, the two phases are uniformly mixed even if the temperature is raised to Tni(PNM) or higher. As a result, it becomes difficult to obtain a polymer-dispersed liquid crystal display device having uniform characteristics.

As a lamp for ultraviolet polymerization, a metal halide lamp, a high-pressure mercury lamp, an extra-high pressure mercury lamp, or the like can be used. In addition, the wavelength of the ultraviolet rays to be irradiated is in the absorption wavelength range of the photopolymerization initiator contained in the light control layer forming material and is not in the absorption wavelength range of the liquid crystal composition contained. Specifically, it is preferable to use a metal halide lamp, a high-pressure mercury lamp, or an ultrahigh-pressure mercury lamp to cut ultraviolet rays of 330 nm or less. It is also preferable to use a UV-LED lamp capable of irradiating a single wavelength.

More specifically, the UV intensity at 313 nm is preferably 10% or less, more preferably 5% or less, and even more preferably 1% or less with respect to the UV intensity at 365 nm. Since the light of 313 nm overlaps with the absorption wavelength of some liquid crystal compounds, it causes deterioration of the liquid crystal compounds and adversely affects the polymerization process. Especially in the case of a liquid crystal composition containing a compound of general formula (II) described below, these phenomena occur remarkably.

The temperature at the time of ultraviolet irradiation is an important factor that determines the properties of the light control layer. As described above, the temperature of the polymer-dispersed liquid crystal composition is preferably Ti(PNM) or higher, more preferably Ti(PNM) +0.1°C or higher to +15.0°C or lower, and Ti(PNM) +0.2°C. From the above, +10.0°C or less is more preferable, and Ti(PNM) +0.3°C or more to +5.0°C or less is most preferable.

Furthermore, when irradiated with ultraviolet rays, the surface on the opposite side of the liquid crystal display element sandwiched between glass substrates or the like and sandwiching the polymer-dispersed liquid crystal composition from the ultraviolet lamp, that is, the state of the back surface of the liquid crystal display element upon ultraviolet irradiation is also uniform. It is an important factor for obtaining a polymer dispersed liquid crystal display device having properties. In the ultraviolet irradiation process, not only the direct light from the ultraviolet lamp but also the reflected light after passing through the liquid crystal display device affects the uniformity of the characteristics. This effect is particularly pronounced in the case of a liquid crystal composition containing a compound of general formula (I-1), which will be described later.

The minimum reflectance of ultraviolet rays on the surface opposite to the ultraviolet lamp when viewed from the liquid crystal display element is preferably 40% or more, more preferably 50% or more, and 70% or more of the maximum reflectance. is even more preferred, and 80% or more is most preferred. In particular, care must be taken when providing a guideline for positioning or the like on the back surface, or when providing a vacuum chuck for fixing the display element. In the case of such specifications, if the influence of reflection during irradiation of ultraviolet rays is not taken into consideration, traces such as vacuum chuck traces are generated on the display element, and a uniform display cannot be obtained. In addition, as the reflectance of ultraviolet rays, the reflectance at 365 nm using the reflection measurement function of the spectrophotometer was evaluated.

The light-modulating layer in the polymer-dispersed liquid crystal display element produced by the above-described method has a droplet structure in which the liquid crystal composition is encapsulated in a polymer substance, and the polymer in the continuous phase of the liquid crystal composition. A structure in which a three-dimensional network structure of a substance is formed, or a structure in which both are mixed, etc. A structure in which a three-dimensional network structure of a transparent polymer substance is formed in a continuous phase of a liquid crystal composition. Preferably.

The average void distance of the network structure greatly affects the characteristics of the polymer-dispersed liquid crystal display device, and the average void distance is preferably 0.2 to 2 μm, more preferably 0.4 to 1.5 μm, and more preferably 0.5 to 0.5 μm. 1.0 μm is most preferred.
(Liquid crystal composition)
The liquid crystal composition used for the polymer-dispersed liquid crystal composition of the present invention preferably contains a compound represented by general formula (I), and may contain two or more kinds of compounds represented by general formula (I). More preferred.

(Wherein, R ¹ represents an alkyl group having 1 to 10 carbon atoms, and one or two non-adjacent CH ₂ groups in the alkyl group are replaced with an oxygen atom, -COO-, -OCO- and one or more methylene groups may be replaced by -CH=CH- or -CH≡CH-,
R ² represents a fluorine atom, chlorine atom, cyano group, CF ₃ group, OCF ₃ group, OCHF ₂ group, NCS group, or an alkyl group having 1 to 10 carbon atoms, and non-adjacent 1 One or two _CH2 groups may be replaced by an oxygen atom, -COO-, -OCO-, and one or more methylene groups may be replaced by -CH=CH- or -C≡C-. preferably a fluorine atom, a cyano group, or an alkyl group having 1 to 5 carbon atoms (one or two non-adjacent CH ₂ groups in the alkyl group may be replaced by an oxygen atom, one or more methylene groups may be replaced by -CH=CH- or -CH≡CH-),
Z ¹ and Z ² are each independently a single bond, -COO-, -OCO-, -CH ₂ -CH ₂ -, -CH=CH-, -CF ₂ O-, -OCF ₂ -, or represents -C≡C-, and when there are a plurality of Z ¹ , they may be the same or different,
A ¹ , A ² and A ³ are each independently a 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, tetrahydropyran-2,5-diyl group, 1 ,3-dioxane-2,5-diyl group, decahydronaphthalene-2,6-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, represents a 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, a 2,6-naphthylene group, the 1,4-phenylene group, 1,2,3,4-tetrahydronaphthalene-2,6- The diyl group, 2,6-naphthylene group may be unsubstituted or may have one or more fluorine atoms, chlorine atoms, _CF3 groups, _OCF3 groups or _CH3 groups as substituents. , A ³ may be the same or different,
n ¹ is 0, 1 or 2)
Among general formula (I), general formula (I-1)

(Wherein, R ¹¹ represents an alkyl group having 1 to 10 carbon atoms, and one or two non-adjacent CH ₂ groups in the alkyl group are replaced with an oxygen atom, —COO—, —OCO— and one or more methylene groups may be replaced by -CH=CH- or -CH≡CH-,
R ¹² represents a fluorine atom, chlorine atom, cyano group, CF ₃ group, OCF ₃ group, OCHF ₂ group, NCS group, or an alkyl group having 1 to 10 carbon atoms, and non-adjacent 1 One or two _CH2 groups may be replaced by an oxygen atom, -COO-, -OCO-, and one or more methylene groups may be replaced by -CH=CH- or -C≡C-. preferably a fluorine atom, a cyano group, or an alkyl group having 1 to 5 carbon atoms (one or two non-adjacent CH ₂ groups in the alkyl group may be replaced by an oxygen atom) and
Z ¹¹ and Z ¹² each independently represent a single bond, -COO-, -OCO-, -CH ₂ -CH ₂ -, -CH=CH-, -CF ₂ O-, -OCF ₂ -, or represents -C≡C-, and when there are a plurality of Z ¹² , they may be the same or different,
A ¹¹ , A ¹² and A ¹³ are each independently a 1,4-phenylene group, a 1,4-cyclohexylene group, a 1,4-cyclohexenyl group, a tetrahydropyran-2,5-diyl group, 1 ,3-dioxane-2,5-diyl group, decahydronaphthalene-2,6-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, represents a 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, a 2,6-naphthylene group, the 1,4-phenylene group, 1,2,3,4-tetrahydronaphthalene-2,6- The diyl group, 2,6-naphthylene group may be unsubstituted or may have one or more fluorine atoms, chlorine atoms, _CF3 groups, _OCF3 groups or _CH3 groups as substituents. , A ¹³ may be the same or different,
ⁿ¹¹ is 0, 1 or 2;
and at least one methylene group in R ¹¹ is replaced by -CH=CH- or -C≡C-, or at least one methylene group in R ¹² is -CH=CH-, or -C≡C-, or Z ¹¹ is -CH=CH-, or -C≡C-, and/or any Z ¹² present is -CH=CH-, or -C≡ is C-. ) more preferably contains one or more compounds, and more preferably contains two or more compounds.

By containing the compound of general formula (I-1), the driving voltage can be further reduced and the scattering property is further improved. The presence of double bonds or triple bonds in these compounds affects the polymerization process of the polymerizable composition when irradiated with ultraviolet rays, and has effects such as reducing the polymerization rate. Also, it becomes easier to control the droplet structure of the polymer. On the contrary, it becomes very susceptible to various conditions in the ultraviolet polymerization process described above. Moreover, it preferably contains both general formula (I-1) and a compound of general formula (I) other than general formula (I-1), more preferably two or more of both.

As compounds of general formula (I) other than general formula (I-1), R ¹ in general formula (I) is an alkyl group having 1 to 5 carbon atoms (one or two CH ₂ groups may be replaced with oxygen atoms), and R ² is a fluorine atom, a cyano group, or an alkyl group having 1 to 5 carbon atoms (non- one or two adjacent CH ₂ groups may be replaced with an oxygen atom), and Z ¹ and Z ² are each independently a single bond, —COO—, —OCO— , —CH ₂ —CH ₂ —, —CF ₂ O—, or —OCF ₂ — (when a plurality of Z ¹ are present, they may be the same or different 9), and a single A bond, —COO—, and —CF ₂ O— are more preferred, and A ¹ , A ² , and A ³ are each independently a 1,4-phenylene group, a 1,4-cyclohexylene group, a 1 ,3-dioxane-2,5-diyl group, pyrimidine-2,5-diyl group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group (the 1,4 -phenylene group, 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, 2,6-naphthylene group is unsubstituted or substituted with one or more fluorine atoms, or CH may have ₃ groups, and when a plurality of A ³ are present, they may be the same or different), preferably 1,4-phenylene group, 1,4-cyclohexylene group, pyrimidine-2,5-diyl group, 2,6-naphthylene group (the 1,4-phenylene group and 2,6-naphthylene group are unsubstituted or substituted with one or more fluorine or a CH ₃ group, and when there are a plurality of A ³ , they may be the same or different), and n ¹ is 0 or 1. Preferably.

In the compound of general formula (I-1), R ¹¹ represents an alkenyl group having 1 to 5 carbon atoms, and R ¹² represents a fluorine atom or an alkyl group having 1 to 5 carbon atoms (in the alkyl group, one or two non-adjacent CH ₂ groups may be replaced with an oxygen atom), Z ¹¹ and Z ¹² each independently represent a single bond, —COO—, —CF ₂ O - represents (when there are a plurality of Z ¹² , they may be the same or different), A ¹¹ , A ¹² and A ¹³ each independently represent a 1,4-phenylene group, 1 ,4-cyclohexylene group (the 1,4-phenylene group may be unsubstituted or may have one or more fluorine atoms or CH ₃ groups as substituents, and A ¹³ is more than one When there are two, the compound may be the same or different), n ¹¹ is 0 or 1,
Alternatively, each of R ¹¹ and R ¹² is independently an alkyl group having 1 to 5 carbon atoms (one or two non-adjacent CH ₂ groups in the alkyl group may be replaced with oxygen atoms). one or more methylene groups may be replaced by -CH=CH-), Z ¹¹ and Z ¹² are each independently a single bond, -COO-, -CF ₂ O -, or -C≡C- (when there are a plurality of Z ¹² , they may be the same or different, but at least one or more Z ¹¹ or Z ¹² represents -C≡C- ), and A ¹¹ , A ¹² and A ¹³ each independently represent a 1,4-phenylene group and a 1,4-cyclohexylene group (the 1,4-phenylene group is unsubstituted or substituted may have one or more fluorine atoms or _CH3 groups as a group, and when there are a plurality of A ¹³ , they may be the same or different), n ¹¹ is preferably a compound representing 0 or 1.

Specifically, compounds represented by the following formulas (II-1) to (II-54) are preferred.

(Polymerizable composition)
The polymer substance forming the network structure and the like in the light control layer is obtained by polymerizing the polymerizable composition (polymerizable monomer composition) in the polymer-dispersed liquid crystal composition. The polymerizable composition is preferably composed of a compound that is cured by heat or ultraviolet rays, and preferably composed of an ultraviolet-curable polymerizable compound. Examples of the UV-curable polymerizable compound include radical polymerization, cationic polymerization, and anionic polymerization, but radically polymerizable compounds are preferred, and acrylic and methacrylic polymerizable compounds are more preferred. Examples of acrylic or methacrylic polymerizable compounds include monofunctional polymerizable compounds and polyfunctional polymerizable compounds. More preferably, it is composed of more than one type of bifunctional polymerizable compound. A more preferred configuration is to use a bifunctional polymerizable compound and a monofunctional polymerizable compound in combination.

The bifunctional polymerizable compound is not particularly limited, but preferably general formula (III-1)

(In the formula, Y ¹ and Y ² represent a hydrogen atom or a methyl group, and X ¹ represents a divalent organic group). The divalent organic group X ¹ preferably has a molecular weight of 150 to 15,000, more preferably 350 to 10,000, and is a group composed of a carbon atom, an oxygen atom, a nitrogen atom, and a hydrogen atom. is preferred.
As X ¹ , if adhesion is the most important, general formula (III-2)

(In the formula, E ¹ represents an alkyl group having 1 to 4 carbon atoms, and one or more —CH ₂ — in the alkyl group is substituted with an oxygen atom, —CO—, —COO—, —OCO— may be, q represents 1 to 20, E ² is the following (III-2-1) ~ (III-2-4)

and E ³ is the following (III-3-1) or (III-3-2)

(wherein Y ³ represents a hydrogen atom or a methyl group, Y ⁵ represents a divalent aromatic group, a divalent alicyclic hydrocarbon group or an alkylene group having 1 to 14 carbon atoms, the alkylene may be substituted with an oxygen atom or -CO- group, Y ⁶ represents an alkylene group having 1 to 14 carbon atoms, the alkylene may be substituted with an oxygen atom or -CO- group, r and y represents 10 to 300.), and if the driving voltage is important, X ¹ is represented by general formulas (III-4-1) to (III-4-3)

(wherein Y ⁴ each independently represents a hydrogen atom or a methyl group, s and t represent an integer of 2 to 15, u represents an integer of 6 to 40, and the formula (III-4- 3) one or more _CH2 groups in may be replaced by an oxygen atom, -CO-, -NH-, -COO-, -OCO-, provided that the oxygen atoms are not directly bonded to each other; One or two hydrogen atoms in the CH ₂ group may be replaced with a methyl group or an ethyl group.) is preferred.

X ¹ is more preferably a compound represented by (III-5-1) or (III-5-2) below.

(In the formula, s1 represents an integer of 3 to 12, and m1+m2 represents an integer of 0 to 6.)
The monofunctional compound is not particularly limited, but is preferably represented by general formula (IV-1)

(In the formula, Y ¹ represents a hydrogen atom or a methyl group, and X ² represents a monovalent organic group).

The monovalent organic group X ² preferably has a molecular weight of 100 to 1000, more preferably 110 to 500, even more preferably 120 to 300, and further preferably a carbon atom, an oxygen atom, and a hydrogen atom. It is preferably a group composed of atoms, and even more preferably does not contain a benzene ring. X ² is more preferably an alkyl group having 8 to 30 carbon atoms which may have a branched group or a cyclic group (one or two or more non-adjacent —CH ₂ - may be independently replaced with an oxygen atom, -COO-, or -OCO-), more preferably an optionally branched alkyl group having 10 to 25 carbon atoms (the alkyl one or more non-adjacent —CH ₂ — in the group may be independently replaced with an oxygen atom, —COO—, or —OCO—), 16 carbon atoms having a branched group Even more preferred is an alkyl group of -24.

It is preferable to use a photopolymerization initiator when forming the polymer material forming the network structure in the light modulating layer by ultraviolet polymerization. The photopolymerization initiator is not particularly limited, but is preferably an intramolecular cleavage initiator such as an alkylphenone type, an acylphosphine oxide type, or an oxime ester type. Specifically, diphenyl-(2,4 ,6-trimethylbenzoyl)phosphine oxide, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenyl-propane -1-one, benzophenone, 1-[4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4- (2-hydroxy-2-methyl-propionyl)-benzyl]-phenyl}-2-methyl-propan-1-one, phenylglyoxylic acid methyl ester, 2-methyl-1-[4-(methylthio)phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone-1, 2-dimethylamino-2-(4-methyl-benzyl)-1 -(4-morpholin-4-yl-phenyl)-butan-1-one, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenyl Phosphine oxide, 1,2-octanedione, 1-[4-(phenylthio)-,2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H -carbazol-3-yl]-,1-(O-acetyloxime), benzophenone, methylbenzoyl formate, oligo{2-hydroxy-2-methyl-1-[4-(1-methylvinyl)phenyl]propanone, 2,4,6 trimethylbenzophenone, 4-methylbenzophenone, 2-ethoxy-1,2-diphenylethan-1-one, 2-(1-methylethoxy)-1,2-diphenylethan-1-one, and 2-isobutoxy-2-phenylacetophenone is preferred.

Among these, 2,2-dimethoxy-1,2-diphenylethan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone, and 2-hydroxy-2-methyl-1-phenyl-propan-1-one are more preferable.

The polymer-dispersed liquid crystal composition used in the polymer-dispersed liquid crystal device of the present invention comprises the aforementioned liquid crystal composition (liquid crystal material), a polymerizable composition, and a polymerization initiator. The ratio (mass ratio) to the polymerizable composition is preferably in the range of 90:10 to 40:60, more preferably 85:15 to 60:40, and 80:20 to 70:30. is even more preferred.

The amount of the polymerization initiator to be added is preferably 0.001 to 3% by mass, more preferably 0.01 to 2% by mass, more preferably 0.1 to 1% by mass in the polymer-dispersed liquid crystal composition. % by weight is even more preferred.

The polymer-dispersed liquid crystal composition used in the polymer-dispersed liquid crystal device of the present invention may contain additives as appropriate in addition to the above compounds. Additives include polymerization inhibitors, antioxidants, light stabilizers such as HALS, dyes, dichroic dyes, and fluorescent dyes.
(Example)
The present invention will be described in more detail with reference to examples below, but the present invention is not limited to these examples. Moreover, "%" in the compositions of the following examples and comparative examples means "% by mass".

Polymer-dispersed liquid crystal display elements in the examples were produced by the following method.

A polymer-dispersed liquid crystal composition containing 78% by mass of liquid crystal composition, 21.6% by mass of polymerizable monomer composition, and 0.4% by mass of photopolymerization initiator was placed in a glass cell with ITO having a cell thickness of 10 μm. The temperature was kept higher than the isotropic-nematic transition point of the polymer dispersed liquid crystal composition, and the composition was injected in an isotropic state. After sealing the injection port with a sealing agent 3026E (manufactured by ThreeBond Co., Ltd.), the metal halide lamp was controlled to a predetermined temperature and adjusted to an irradiation intensity of 20 mW/cm ² via a UV cut filter as necessary. was irradiated for 60 seconds to obtain a polymer dispersed liquid crystal display device. A rear plate shown in FIG. 1 was placed on the rear surface during UV irradiation.

Soda-lime glass having a thickness shown in Table 1 was appropriately used as a UV cut filter.

After being injected into the glass cell in an isotropic state, it was allowed to stand under the conditions shown in Table 2 for 1 minute, and UV irradiation was performed.

White copy paper (region (1)) was used as the back plate, and paint was applied to the shaded region (2) in FIG. 1 under the conditions shown in Table 3 below. Note that condition B1 is the same member as the white copy paper in (1) without coating. Condition B4 is nothing, that is, air, and nothing 30 cm below (2) (assuming a vacuum chuck).

The abbreviations and meanings of the properties of the liquid crystal compositions and polymer-dispersed liquid crystal compositions shown in the examples are as follows.

Tni(LC): Nematic phase-isotropic liquid phase transition temperature of liquid crystal composition (°C)
Δn: Refractive index anisotropy of liquid crystal composition at 25° C. Tni (PNM): Nematic phase-isotropic liquid phase transition temperature of polymer dispersed liquid crystal composition (° C.)
T0: Transmittance (%) of the polymer dispersed liquid crystal element when the voltage is off, with the cell thickness of 10 μm, 25° C., and the amount of light when nothing (air) is taken as 100%.

T100: Transmittance (%) when 50 V is applied to the polymer dispersed liquid crystal element at a cell thickness of 10 μm and 25° C., where the amount of light when there is nothing (air) is taken as 100%.

V90: When the light transmittance (T0) of the polymer dispersed liquid crystal element when no voltage is applied is 0% and the light transmittance (T100) when 50 V is applied is 100% at a cell thickness of 10 µm and 25°C, Applied voltage value (V) at which light transmittance is 90%.

The evaluation method is as follows.

A temperature control system FP-90 and a hot stage FP82 manufactured by Mettler Toledo were used for the transition point measurement.

To measure T0, T100, and V90, an LCD evaluation system LCD-5200 manufactured by Otsuka Electronics Co., Ltd. was used, and measurements were made under the conditions of B lens and aperture S. At that time, measurements were made at 100 points for each square as shown in FIG. 2 for each cell.

From the evaluation value of T0, calculate the average value of the top 10% of in-plane transmittance (A) and the average value (B) of the bottom 10%, and evaluate the value of (AB) / B × 100 as the degree of unevenness. bottom.

In addition, it was also evaluated whether the difference in transmittance in the cell plane can be determined visually. Table 4 shows the criteria.

The refractive index was measured using an Ape's refractometer (manufactured by ATAGO).

As the reflectance at 365 nm, a UV-visible-near-infrared spectrophotometer U-4100 manufactured by Hitachi, Ltd. was used.

The UV intensity was measured using a Ushio Inc. UIT-250 with sensors of 365 nm and 313 nm.

The following composition was used as the liquid crystal composition.

(Liquid Crystal Composition LC1) Δn=0.226, Tni(LC)=87.4°C

(Liquid Crystal Composition LC2) Δn=0.218, Tni(LC)=73.9°C

(Liquid Crystal Composition LC3) Δn=0.219, Tni(LC)=83.8°C

(Liquid Crystal Composition LC4) Δn=0.226, Tni(LC)=73.8°C

As the monomer composition, a composition of the following compounds was used.
(Monomer composition a)

The following compounds were used as photopolymerization initiators.

(Examples 1 to 12, Comparative Examples 1 to 6)
Tables 5 to 9 describe the conditions and evaluation results of Examples and Comparative Examples 1 to 6. The maximum Ave. in the table is the average value of the top 10% of in-plane transmittance T0, and the average value of T100 and V90 at that point, and the minimum Ave. It represents the mean of T100 and V90 at that point. The average value represents the overall average value.

From the results of Examples and Comparative Examples, it can be seen that the appearance of the display element varies depending on the reflection conditions of the back surface of the panel, and it can also be understood that the difference varies depending on the liquid crystal composition. By adopting the method for manufacturing a polymer dispersed liquid crystal display element of the present invention, a polymer dispersed liquid crystal display element having unprecedented uniform characteristics such that unevenness is completely unnoticeable or unnoticeable visually when no voltage is applied. A liquid crystal display device was produced.

Claims (8)

Between two substrates, at least one of which has an electrode layer and at least one of which is transparent, a liquid crystal material and a light modulating layer-forming material containing a polymerizable composition are interposed between the substrates. By polymerizing a polymerizable composition, it has a light control layer composed of a liquid crystal material and a polymer substance, and the average value A of the top 10% and the average value B of the bottom 10% in the transmittance distribution of the light control layer In a method for manufacturing a polymer dispersed liquid crystal display element in which the ratio ((AB)/B×100) of the difference (A−B) to the average value B of the lower 10% is 200% or less,
The liquid crystal material has the general formula (I −1 )

(Wherein, R ¹¹ represents an alkyl group having 1 to 10 carbon atoms, and one or two non-adjacent CH ₂ groups in the alkyl group are replaced with an oxygen atom, —COO—, —OCO— and one or more methylene groups may be replaced by -CH=CH- or -CH≡CH-,
R ¹² represents a fluorine atom, chlorine atom, cyano group, CF ₃ group, OCF ₃ group, OCHF ₂ group, NCS group, or an alkyl group having 1 to 10 carbon atoms, and non-adjacent 1 One or two CH2 _groups may be replaced by an oxygen atom, -COO-, -OCO-, and one or more methylene groups may be replaced by -CH=CH- or -C≡C-. may be
Z ¹¹ and Z ¹² each independently represent a single bond, -COO-, -OCO-, -CH ₂ -CH ₂ -, -CH=CH-, -CF ₂ O-, -OCF ₂ -, or represents -C≡C-, and when there are a plurality of Z ¹² , they may be the same or different,
A ¹¹ , A ¹² and A ¹³ are each independently a 1,4-phenylene group, a 1,4-cyclohexylene group, a 1,4-cyclohexenyl group, a tetrahydropyran-2,5-diyl group, 1 ,3-dioxane-2,5-diyl group, decahydronaphthalene-2,6-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, represents a 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, a 2,6-naphthylene group, the 1,4-phenylene group, 1,2,3,4-tetrahydronaphthalene-2,6- The diyl group, 2,6-naphthylene group may be unsubstituted or may have one or more fluorine atoms, chlorine atoms, _CF3 groups, OCF3 _groups or CH3 _groups as substituents. , A ¹³ may be the same or different,
n11 is 0, 1 or 2 ^;
and Z ¹¹ is -CH=CH- or -C≡C- and/or any Z ¹² present is -CH=CH- or -C≡C-. )
Contains one or more compounds represented by
A polymer-dispersed type characterized in that the minimum reflectance of ultraviolet rays on the installation surface of the liquid crystal display element located on the opposite side of the ultraviolet irradiation lamp as viewed from the liquid crystal display element irradiated with ultraviolet rays is 50% or more of the maximum reflectance. A method for manufacturing a liquid crystal display element. Z in the general formula (I-1) ¹¹ is -C≡C- and/or there is Z ¹² is -C≡C-. The polymerizable composition according to claim 1 has the general formula (IV-1)

(In the formula, Y ¹ represents a hydrogen atom or a methyl group, X ² represents an alkyl group having 8 to 30 carbon atoms which may have a branched group or a cyclic group (non-adjacent One or more —CH ₂ — may be independently replaced with an oxygen atom, —COO—, or —OCO—). A method for manufacturing a polymer dispersed liquid crystal display element. After interposing the light-modulating layer-forming material between the two substrates, the material is maintained at a temperature equal to or higher than the nematic-isotropic transition point of the light-modulating layer-forming material until the ultraviolet irradiation is performed, and even during the ultraviolet irradiation. 4. The method for producing a polymer dispersed liquid crystal display element according to claim 1, wherein the temperature is controlled to a nematic-isotropic transition point or higher. 5. The production of the polymer dispersed liquid crystal display element according to any one of claims 1 to 4, characterized in that the intensity of ultraviolet rays at 313 nm is 10% or less of that at 365 nm. Method. Between two substrates, at least one of which has an electrode layer and at least one of which is transparent, a light control layer made of a liquid crystal material and a polymeric substance that is a polymer of a polymerizable composition is provided, The ratio of the difference (A - B) between the average value A of the top 10% and the average value B of the bottom 10% in the layer transmittance distribution to the average value B of the bottom 10% ((A - B) / B x 100 ) is 200% or less,
The liquid crystal material has the general formula (I −1 )

(Wherein, R ¹¹ represents an alkyl group having 1 to 10 carbon atoms, and one or two non-adjacent CH ₂ groups in the alkyl group are replaced with an oxygen atom, —COO—, —OCO— and one or more methylene groups may be replaced by -CH=CH- or -CH≡CH-,
R ¹² represents a fluorine atom, chlorine atom, cyano group, CF ₃ group, OCF ₃ group, OCHF ₂ group, NCS group, or an alkyl group having 1 to 10 carbon atoms, and non-adjacent 1 One or two CH2 _groups may be replaced by an oxygen atom, -COO-, -OCO-, and one or more methylene groups may be replaced by -CH=CH- or -C≡C-. may be
Z ¹¹ and Z ¹² each independently represent a single bond, -COO-, -OCO-, -CH ₂ -CH ₂ -, -CH=CH-, -CF ₂ O-, -OCF ₂ -, or represents -C≡C-, and when there are a plurality of Z ¹² , they may be the same or different,
A ¹¹ , A ¹² and A ¹³ are each independently a 1,4-phenylene group, a 1,4-cyclohexylene group, a 1,4-cyclohexenyl group, a tetrahydropyran-2,5-diyl group, 1 ,3-dioxane-2,5-diyl group, decahydronaphthalene-2,6-diyl group, pyridine-2,5-diyl group, pyrimidine-2,5-diyl group, pyrazine-2,5-diyl group, represents a 1,2,3,4-tetrahydronaphthalene-2,6-diyl group, a 2,6-naphthylene group, the 1,4-phenylene group, 1,2,3,4-tetrahydronaphthalene-2,6- The diyl group, 2,6-naphthylene group may be unsubstituted or may have one or more fluorine atoms, chlorine atoms, _CF3 groups, OCF3 _groups or CH3 _groups as substituents. , A ¹³ may be the same or different,
n11 is 0, 1 or 2 ^;
and Z ¹¹ is -CH=CH- or -C≡C- and/or any Z ¹² present is -CH=CH- or -C≡C-. )
Contains one or more compounds represented by
The light modulating layer is a polymer dispersed liquid crystal display element in which a network structure of the polymer substance is formed in the continuous phase of the liquid crystal material, and an average gap distance of the network structure is 0.2 to 2 μm. . Z in the general formula (I-1) ¹¹ is -C≡C- and/or there is Z ¹² 7. The polymer dispersed liquid crystal display device according to claim 6, wherein is -C≡C-. The polymerizable composition according to claim 6 has the general formula (IV-1)

(In the formula, Y ¹ represents a hydrogen atom or a methyl group, X ² represents an alkyl group having 8 to 30 carbon atoms which may have a branched group or a cyclic group (non-adjacent One or more —CH ₂ — may be independently replaced with an oxygen atom, —COO—, or —OCO—.). Polymer dispersed liquid crystal display element.

Images